Epstein-Barr virus latent membrane protein 1 trans-activates miR-155 transcription through the NF-kappaB pathway.
The Epstein-Barr virus (EBV)-encoded latent membrane protein-1 (LMP1), a functional homologue of the tumor necrosis factor receptor family, substantially contributes to EBV's oncogenic potential by activating nuclear factor-kappaB (NF-kappaB). miR-155 is an oncogenic miRNA critical for B-cell maturation and immunoglobulin production in response to antigen. We report that miR-155 expression is much higher in EBV-immortalized B cells than in EBV-negative B cells. LMP1, but not LMP2, up-regulated the expression of miR-155, when transfected in EBV-negative B cells. We analyzed two putative NF-kappaB binding sites in the miR-155 promoter; both sites recruited NF-kappaB complex, in nuclear extract from EBV-immortalized cells. The exogenous expression of LMP1, in EBV-negative background, is temporally correlated to induction of p65 with binding on both NF-kappaB sites and with miR-155 overexpression. The induction of p65 binding together with increased RNA polymerase II binding, confirms that LMP1-mediated activation of miR-155 occurs transcriptionally. In reporter assays, miR-155 promoter lacking NF-kappaB binding sites was no longer activated by LMP1 expression and an intact AP1 site is needed to attain maximum activation. Finally, we demonstrate that LMP1-mediated activation of miR-155 in an EBV-negative background correlates with reduction of protein PU.1, which is a possible miR target.
Gatto
Graziana
G
Department of Biochemistry and Medical Biotechnologies, University of Naples Federico II, Naples, Italy.
Rossi
Annalisa
A
Rossi
Daniela
D
Kroening
Sven
S
Bonatti
Stefano
S
Mallardo
Massimo
M
D000818:Animals; D001402:B-Lymphocytes / Q000821:virology*; D001665:Binding Sites; D002460:Cell Line; D002478:Cells, Cultured; D004854:Herpesvirus 4, Human / Q000502:physiology; D006801:Humans; D051379:Mice; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics*; D016328:NF-kappa B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism; D015533:Transcriptional Activation; D014763:Viral Matrix Proteins / Q000378:metabolism*; D000099232:Proto-Oncogene Protein Spi-1
D035683:MicroRNAs; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D015534:Trans-Activators; D051996:Transcription Factor RelA; D014763:Viral Matrix Proteins; D000099232:Proto-Oncogene Protein Spi-1; C037662:EBV-associated membrane antigen, Epstein-Barr virus; C524942:MIRN155 microRNA, human